The field of cardiovascular interventional therapy has experienced three milestone leaps from the 70's in last century to now. In 1977, a balloon was used for the first time to dilate coronary artery stenosis in a human, as the first milestone. Although the balloon dilation could eliminate the coronary artery stenosis, due to the elasticity recoil of the vascular wall, intimal hyperplasia and vascular wall intimal tear and the like, vascular restenosis may re-occur again, and the restenosis rate of the target vessel reaches up to 30 to 50% after post-operative 3 to 6 months. The advent of a bare metal stent in 1986, is the second milestone of the interventional therapy, which could not only eliminate the short-term vascular stenosis, but could also greatly reduce the acute occlusion rate. However, the restenosis rate of the target vessel can still reach up to 30%. A drug eluting stent came out in 2001, as the third milestone, to reduce the restenosis rate of the target vessel to below 3%.
The stent may treat the atherosclerosis and the vascular stenosis, but the risk of restenosis will still exist in the blood vessel and the stent, and the therapeutic effect of the stent on small vessels, bifurcation vessels, in situ lesions and the like is not ideal. At present, the method for treating restenosis includes re-dilatation using a conventional balloon, oriented atherectomy, rotational atherectomy, endovascular radiotherapy, repeated stenting, and so on. The existing uncoated balloons and drug eluting stents all have certain limitations. The restenosis rate of the uncoated balloon is higher, and the therapeutic effect of the drug eluting stent on small vessels and bifurcation vessels is poor; both of the uncoated balloon and the drug eluting stent fail to show sufficient effectiveness or safety thereof.
The advent of a drug eluting balloon has brought a new hope to treat restenosis. The prior drug coated balloon treats the coronary artery restenosis by applying a drug coating on the balloon catheter, with a contrast agent iopromide as a carrier together with paclitaxel regarded as the drug coating, which may improve the drug transfer rate. However, the contrast agent in the diagnostic process can provide a certain incidence of complications. Moreover, as a large hydrophilic molecule, the iopromide might not effectively carry the lipophilic paclitaxel to penetrate through the membrane lipid bilayer into the cell.
The key technical point of the drug coated balloon is how to achieve a bond balance between the drug coating and the surface of the balloon. If the adhesive force between the drug coating and the surface of the balloon is smaller, the drug can easily fall off during the folding of the balloon, or be lost during the delivery process for placing at a lesion site, or could burst and fall off in the expansion process before coming in contact with the target tissue, and then flushed away by the high speed flowed blood. If the adhesive force between the drug coating and the surface of the balloon is too large, the drug cannot be easily transferred to the tissue when the balloon contacts the target lesion tissue.